title: Laser speckle contrast imaging: theoretical and practical limitations.
abstract: When laser light illuminates a diffuse object, it produces a random interference effect known as a speckle pattern. If there is movement in the object, the speckles fluctuate in intensity. These fluctuations can provide information about the movement. A simple way of accessing this information is to image the speckle pattern with an exposure time longer than the shortest speckle fluctuation time scale-the fluctuations cause a blurring of the speckle, leading to a reduction in the local speckle contrast. Thus, velocity distributions are coded as speckle contrast variations. The same information can be obtained by using the Doppler effect, but producing a two-dimensional Doppler map requires either scanning of the laser beam or imaging with a high-speed camera: laser speckle contrast imaging (LSCI) avoids the need to scan and can be performed with a normal CCD- or CMOS-camera. LSCI is used primarily to map flow systems, especially blood flow. The development of LSCI is reviewed and its limitations and problems are investigated.
authors.affiliation: Kingston University, United Kingdom. David.Briers@physics.org
authors.forename: David
authors.initials: D
authors.lastname: Briers
authors.forename: Donald D
authors.initials: DD
authors.lastname: Duncan
authors.forename: Evan
authors.initials: E
authors.lastname: Hirst
authors.forename: Sean J
authors.initials: SJ
authors.lastname: Kirkpatrick
authors.forename: Marcus
authors.initials: M
authors.lastname: Larsson
authors.forename: Wiendelt
authors.initials: W
authors.lastname: Steenbergen
authors.forename: Tomas
authors.initials: T
authors.lastname: Stromberg
authors.forename: Oliver B
authors.initials: OB
authors.lastname: Thompson
mesh_terms: D000465:Algorithms; D001783:Blood Flow Velocity; D003287:Contrast Media / Q000494:pharmacology; D004912:Erythrocytes / Q000473:pathology; D006801:Humans; D007834:Lasers; D008833:Microcirculation / Q000502:physiology*; D055095:Optics and Photonics; D010477:Perfusion; D012039:Regional Blood Flow; D012171:Retinal Vessels / Q000473:pathology; D018608:Ultrasonography, Doppler / Q000379:methods
chemical_list: D003287:Contrast Media